The present invention relates to hologram laminates wherein, in order to verify that goods are genuine, a hologram label has been applied onto substrates, for example, those having monetary values, such as gold notes or securities, those as identification means for identifying the holder, such as identification cards or papers or credit cards, high-priced goods, such as high-grade watches, or gift boxes for these goods.
The present invention relates also to hologram application labels suitable for such applications.
The hologram laminates and the hologram labels according to the present invention having a special structure such that, when they are applied to a substrate followed by separation, a protective film as the surface film is separated while leaving a part of a pressure-sensitive adhesive on the hologram, or otherwise causes the separation of other layer while leaving a part of a pressure-sensitive adhesive on the separated portion, or when the exposed hologram is separated, the hologram is elongated, and that, as a result, in any event, a clear evidence of the separation is left.
The hologram per se is a product of photographic technology known for long, and has been formed by applying interference fringes, produced by interference of two laser beams, that is, reference light and object light containing information of an object, onto a photographic plate and conducting development to obtain the hologram as a silver salt photograph. In recent years, a relief hologram formed by applying interference fringes to a photosensitive resin and conducting development to record the interference fringes as concaves and convexes on the surface of the resin has become possible to be mass-duplicated by virtue of a duplication technique using a resin, and has become extensively used in various applications. In particular, since the hologram is difficult to produce, the hologram has been applied, as one of measures for the prevention of forgery, to various articles.
On the other hand, a volume hologram is among the holograms. In the volume hologram, interference fringes are three dimensionally recorded in the thicknesswise direction of a photosensitive resin. For example, the development of photosensitive resins and the development of peripheral technology in recent years have enabled mass production of the volume hologram. Although the volume hologram is duplicated using a photosensitive resin, the mechanical strength thereof is lower than that of the relief hologram formed of a fully cured resin. Further, in the application of the volume hologram to various applications, direct fabrication into a hologram layer is difficult. This restricts the prevention of forgery.
The volume hologram is difficult to produce as with the relief hologram. However, when a person obtains a genuine hologram, is separated from the hologram applied site, and is then applied to other article, since the hologram per se is genuine, it is very difficult to judge whether or not an illegal act has been made.
For this reason, various techniques have been proposed for preventing the replacement of the genuine hologram particularly in the latter hologram.
For example, Japanese Patent Laid-Open No. 86565/1998 describes a hologram laminate comprising a substrate and, applied onto the substrate, a hologram having thereon a transparent protective sheet, wherein distribution of adhesive strength is provided within the face of any one of an adhesive layer for adhering a transparent protective sheet to a hologram and an adhesive layer for adhering the hologram to a substrate and an attempt to conduct separation causes breaking of the hologram, thereby preventing the replacement of the hologram.
In order to create the distribution of the adhesive strength, two types of adhesives are used. This complicates working. Further, when different types of adhesives are used, there is a fear that the adoption of this technique becomes apparent from the appearance due to the difference in refractive index between these types of adhesives.
Japanese Patent Laid-Open No. 133552/1998 describes the same layer construction as described above, except that the tackiness of the pressure-sensitive adhesive layer between the protective film and the volume hologram layer is made lower than the tackiness of pressure-sensitive adhesive layer between the substrate and the volume hologram layer. In this technique, an attempt to conduct separation, a “peel line” is formed at a right angle to the direction of the separation, leaving an evidence of the separation.
Since, however, the peel line is not previously formed at a predetermined position but formed in the course of the separation, the state of the formation of the peel line varies depending upon, for example, the direction pulled and the force applied in the separation. Therefore, the certainty of the formation of the peel line is open to question.
Accordingly, it is an object of the first invention to provide a hologram laminate and a hologram label which has no problem in the production process thereof, has certainty in the process for attaining the forgery preventive effect, and can make it difficult to find out the evidence of the working for forgery preventive purposes.
In addition to use in display of three-dimensional images, measurement, optical elements and the like, the hologram, by virtue of the necessity of advanced techniques and specialty apparatus in the production of the hologram and the difficulty of forging the hologram, is often applied to materials for verifying that the holder is truly a qualified person, such as identification cards or papers, or to goods and the like which should be verified to be genuine.
For example, for some credit cards, a hologram is stacked onto the surface thereof to verify that the card has been prepared through prescribed procedures. Further, a hologram is formed on a part of the surface of gold notes having values similar to money, such as tickets for goods. Furthermore, a hologram is often applied onto the surface of goods, for example, the surface of the case for selling of high-grade watches and the surface of the cassette half of videotapes having a fear of unauthorized tapes being spread.
In all the above cases, when the hologram is illegally separated and is successfully diverted to other object, since the hologram per se is not a forged one, a credit card, which is not originally valid, is seen like a valid one. In this case, also in the case of forged gold notes or goods, erroneous assumption of the forged notes or goods as genuine notes or goods are likely to occur.
These adherends, onto which the hologram is applied, have respective values. Gold notes and goods usually have economical values within the face value or the price of the genuine goods. On the other hand, since credit cards guarantee credit per se, in some cases, there is a fear of a vast sum of money being lost. Therefore, the prevention of the forgery of the credit card is of great social significance.
In the credit card, in addition to the hologram, a photograph of the face or an autograph of the holder is provided on the surface of the card from the viewpoint of ensuring the security. If the hologram is integral with and inseparable from the credit card, it is difficult to conduct forgery. In fact, however, unfortunately, it is not impossible to separate the hologram from the credit card although this separation is difficult.
Therefore, a person obtains an unused credit card, conducts necessary working, and applies a hologram separated from a properly published credit card onto the worked credit card, the forged credit card apparently should be regarded as a genuine one.
Accordingly, it is an object of the second invention to provide a hologram laminate, having high forgery preventive properties, wherein, in objects typified by credit cards and the like, for each object, for example, for each card, inherent information has been made inseparable from the hologram, and a process for producing the same.
As described above, for some credit cards, a hologram is stacked onto a photograph of the face or an autograph provided on the surface of the credit card. In this case, however, when the hologram is illegally separated and is successfully diverted to other object, since the hologram per se is not a forged one, a credit card, which is not originally valid, is seen like a valid one. In this case, also in the case of forged gold notes or goods, erroneous assumption of the forged notes or goods as genuine notes or goods are likely to occur.
In the forgery of an unused substrate for credit cards, since any forgery preventive means, such as watermark in paper money, is not used in the substrate for credit cards, the outside of the substrate can be duplicated by the photomechanical process.
Likewise, for various certificates, securities, stock certificates, gold notes and the like, a ground tint or the like is printed on papers to prevent forgery. The forgery, however, is not impossible. Although the judgment of the forgery is possible, magnification or a special technique has often been required for the judgment.
Forgery of these papers incurs a loss corresponding to the preparation cost. In addition, the economical loss caused by the use of the forged papers is huge. Therefore, taking measures to prevent the forgery is of high social significance.
Accordingly, it is an object of the third invention to provide an improved product wherein, regarding not only credit cards or the like but also various articles in a sheet form or articles in other forms, for example, patterns, such as ground tints or figures, or coloration formed mainly by printing and the like cannot be easily duplicated by mere copying of the shape and color tone.
In recent years, the volume hologram, by virtue of the difficulty of forging the hologram per se, has become used as the so-called security label, for example, in the application onto identification cards or papers or as breaking seal of confidential documents and the like, and in the application onto CD. In this hologram, however, there is a fear of the hologram-applied medium being forged in such a manner that a hologram laminate is separated from the hologram-applied medium and is again applied.
In order to prevent the forgery of the hologram-applied medium by the re-application, a construction has been used wherein, upon the separation of a hologram laminate, the hologram laminate is broken and even the re-application of the hologram laminate cannot reproduce the original state before the separation. Such hologram laminates include a type wherein, after the application of the hologram laminate, an attempt to separate the hologram laminate causes the separation of the substrate alone and a type wherein, after the application of the hologram laminate, an attempt to separate the hologram laminate causes an adhesive to be partially left. Leaving of a part of the hologram laminate poses a problem in applications where, after the use of a label for the judgment on whether the object is a genuine one or a forged one, the label is removed.
Japanese Patent Laid-Open Nos. 86565/1998 and 153944/1998 and the like describe a method wherein the dynamical properties of the volume hologram layer and the pressure-sensitive adhesive layer are optimized so that an attempt to separate a hologram laminate causes breaking of the hologram layer, and a method wherein distribution is provided in the peel strength of the pressure-sensitive adhesive so that an attempt to separate a hologram laminate causes breaking of the hologram layer. In the method wherein the hologram-applied medium is separated, in some cases, the hologram laminate can be separated without breaking the hologram layer. Therefore, the forgery preventive effect is not perfect, and a higher level of security has been demanded in the art. Further, in this hologram laminate, the forgery preventive effect by the breaking of the hologram layer varies depending upon the adhesion to media, on which the hologram laminate is applied.
Accordingly, it is an object of the fourth invention to provide a volume hologram laminate and a label for the preparation of a volume hologram laminate which, upon the separation of the hologram laminate from the hologram-applied medium, can surely cause breaking of the hologram layer and, at the same time, enables the hologram laminate in its broken part left on the medium to be easily removed from the application medium, such as an identification card or paper, and, in addition, can be suitably used for application media having various adhesive properties.